The invention relates generally to aircraft control systems and more particularly concerns an aircraft flight path angle control system that employs direct lift control.
The flight path angle is the angle between the aircraft's inertial velocity vector and the local horizontal reference plane. In the past, pilot-controlled Stability Augmentation Systems (SAS) designed to control the flight path angle have utilized the aircraft's elevators (or horizontal stabilizers) for the control. The main disadvantage with these systems is there is a delay between the time the pilot changes the position of the elevators and the time the flight path angle changes in response thereto. Also with elevator control there is limited ability to counteract short term flight path fluctuation due to environmental disturbances.
It is the primary object of this invention to provide a pilot-controlled SAS that decreases the delay between the time that the pilot actuates his control until the time that the flight path angle changes in response thereto.
Another object of this invention is to provide short term flight path angle stabilization due to environmental disturbances.
Other objects and advantages of this invention will become apparent hereinafter and in the drawings.